Subject: [PATCH 02/18] KVM: ARM64: Add initial support for PMU

From: [email-masked] (Shannon Zhao)
Date: Fri, 17 Jul 2015 16:13:35 +0800

On 2015/7/17 2:25, Christoffer Dall wrote:
> On Mon, Jul 06, 2015 at 10:17:32AM +0800, shannon.zhao at linaro.org wrote:
>> From: Shannon Zhao <[email-masked]>
>>
>> Here we plan to support virtual PMU for guest by full software
>> emulation, so define some basic structs and functions preparing for
>> futher steps. Define struct kvm_pmc for performance monitor counter and
>> struct kvm_pmu for performance monitor unit for each vcpu. According to
>> ARMv8 spec, the PMU contains at most 32(ARMV8_MAX_COUNTERS) counters.
>> Initialize PMU for each vcpu when kvm initialize vcpus, while reset PMU
>> when kvm reset vcpus.
>> Since this only supports ARM64 (or PMUv3), add a separate config symbol
>> for it.
>>
>> Signed-off-by: Shannon Zhao <[email-masked]>
>> ---
>>  arch/arm/kvm/arm.c                |  4 +++
>>  arch/arm64/include/asm/kvm_host.h |  2 ++
>>  arch/arm64/include/asm/pmu.h      |  2 ++
>>  arch/arm64/kvm/Kconfig            |  7 +++++
>>  arch/arm64/kvm/Makefile           |  1 +
>>  arch/arm64/kvm/reset.c            |  3 +++
>>  include/kvm/arm_pmu.h             | 54 ++++++++++++++++++++++++++++++++++++++
>>  virt/kvm/arm/pmu.c                | 55 +++++++++++++++++++++++++++++++++++++++
>>  8 files changed, 128 insertions(+)
>>  create mode 100644 include/kvm/arm_pmu.h
>>  create mode 100644 virt/kvm/arm/pmu.c
>>
>> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
>> index bc738d2..4e82625 100644
>> --- a/arch/arm/kvm/arm.c
>> +++ b/arch/arm/kvm/arm.c
>> @@ -28,6 +28,7 @@
>>  #include <linux/sched.h>
>>  #include <linux/kvm.h>
>>  #include <trace/events/kvm.h>
>> +#include <kvm/arm_pmu.h>
>>  
>>  #define CREATE_TRACE_POINTS
>>  #include "trace.h"
>> @@ -278,6 +279,9 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
>>  	/* Set up the timer */
>>  	kvm_timer_vcpu_init(vcpu);
>>  
>> +	/* Set up the PMU */
>> +	kvm_pmu_init(vcpu);
>> +
>>  	return 0;
>>  }
>>  
>> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
>> index 2709db2..3c88873 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -42,6 +42,7 @@
>>  
>>  #include <kvm/arm_vgic.h>
>>  #include <kvm/arm_arch_timer.h>
>> +#include <kvm/arm_pmu.h>
>>  
>>  #define KVM_VCPU_MAX_FEATURES 3
>>  
>> @@ -116,6 +117,7 @@ struct kvm_vcpu_arch {
>>  	/* VGIC state */
>>  	struct vgic_cpu vgic_cpu;
>>  	struct arch_timer_cpu timer_cpu;
>> +	struct kvm_pmu pmu;
>>  
>>  	/*
>>  	 * Anything that is not used directly from assembly code goes
>> diff --git a/arch/arm64/include/asm/pmu.h b/arch/arm64/include/asm/pmu.h
>> index b9f394a..95681e6 100644
>> --- a/arch/arm64/include/asm/pmu.h
>> +++ b/arch/arm64/include/asm/pmu.h
>> @@ -19,6 +19,8 @@
>>  #ifndef __ASM_PMU_H
>>  #define __ASM_PMU_H
>>  
>> +#include <linux/perf_event.h>
>> +
>>  #define ARMV8_MAX_COUNTERS      32
>>  #define ARMV8_COUNTER_MASK      (ARMV8_MAX_COUNTERS - 1)
>>  
>> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
>> index bfffe8f..eae3a1b 100644
>> --- a/arch/arm64/kvm/Kconfig
>> +++ b/arch/arm64/kvm/Kconfig
>> @@ -31,6 +31,7 @@ config KVM
>>  	select KVM_VFIO
>>  	select HAVE_KVM_EVENTFD
>>  	select HAVE_KVM_IRQFD
>> +	select KVM_ARM_PMU
>>  	---help---
>>  	  Support hosting virtualized guest machines.
>>  
>> @@ -52,4 +53,10 @@ config KVM_ARM_MAX_VCPUS
>>  	  large, so only choose a reasonable number that you expect to
>>  	  actually use.
>>  
>> +config KVM_ARM_PMU
>> +	bool
>> +	depends on KVM_ARM_HOST
>> +	---help---
>> +	  Adds support for the Performance Monitoring in virtual machines.
> 
> Adds support for a virtual Performance Monitoring Unit (PMU) in virtual
> machines.
> 
>> +
>>  endif # VIRTUALIZATION
>> diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
>> index f90f4aa..78db4ee 100644
>> --- a/arch/arm64/kvm/Makefile
>> +++ b/arch/arm64/kvm/Makefile
>> @@ -27,3 +27,4 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic-v3.o
>>  kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic-v3-emul.o
>>  kvm-$(CONFIG_KVM_ARM_HOST) += vgic-v3-switch.o
>>  kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/arch_timer.o
>> +kvm-$(CONFIG_KVM_ARM_PMU) += $(KVM)/arm/pmu.o
>> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
>> index 0b43265..ee2c2e9 100644
>> --- a/arch/arm64/kvm/reset.c
>> +++ b/arch/arm64/kvm/reset.c
>> @@ -107,5 +107,8 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
>>  	/* Reset timer */
>>  	kvm_timer_vcpu_reset(vcpu, cpu_vtimer_irq);
>>  
>> +	/* Reset PMU */
>> +	kvm_pmu_vcpu_reset(vcpu);
>> +
>>  	return 0;
>>  }
>> diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
>> new file mode 100644
>> index 0000000..27d14ca
>> --- /dev/null
>> +++ b/include/kvm/arm_pmu.h
>> @@ -0,0 +1,54 @@
>> +/*
>> + * Copyright (C) 2015 Linaro Ltd.
>> + * Author: Shannon Zhao <[email-masked]>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#ifndef __ASM_ARM_KVM_PMU_H
>> +#define __ASM_ARM_KVM_PMU_H
>> +
>> +#include <asm/pmu.h>
>> +#include <linux/irq_work.h>
>> +
>> +struct kvm_pmc {
>> +	u8 idx;
> 
> which index is this?  Does it map to something architecturally or is it
> just the array index number?
> 

It's the index of the PMU counter.

>> +	u64 counter;
>> +	u64 eventsel;
> 
> does this map to PMEVTYPER<n>_EL0.evtCount?
> 
No, it just stores the event type.

>> +	bool interrupt;
> 
> is this that an interrupt which is pending or which is enabled?
> 
>> +	bool enable;
>> +	struct perf_event *perf_event;
>> +	struct kvm_vcpu *vcpu;
>> +};
>> +
>> +struct kvm_pmu {
>> +#ifdef CONFIG_KVM_ARM_PMU
>> +	/* PMU IRQ Number per VCPU */
>> +	int irq_num;
>> +	int overflow_status;
>> +	/* IRQ pending flag */
>> +	bool irq_pending;
>> +	struct irq_work irq_work;
>> +	struct kvm_pmc pmc[ARMV8_MAX_COUNTERS];
>> +#endif
>> +};
>> +
>> +#ifdef CONFIG_KVM_ARM_PMU
>> +void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu);
>> +void kvm_pmu_init(struct kvm_vcpu *vcpu);
>> +#else
>> +static inline void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu) {}
>> +static inline void kvm_pmu_init(struct kvm_vcpu *vcpu) {}
>> +#endif
>> +
>> +#endif
>> diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
>> new file mode 100644
>> index 0000000..dc252d0
>> --- /dev/null
>> +++ b/virt/kvm/arm/pmu.c
>> @@ -0,0 +1,55 @@
>> +/*
>> + * Copyright (C) 2015 Linaro Ltd.
>> + * Author: Shannon Zhao <[email-masked]>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include <linux/cpu.h>
>> +#include <linux/kvm.h>
>> +#include <linux/kvm_host.h>
>> +#include <kvm/arm_pmu.h>
>> +
>> +/**
>> + * kvm_pmu_vcpu_reset - reset pmu state for cpu
>> + * @vcpu: The vcpu pointer
>> + *
>> + */
>> +void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu)
>> +{
>> +	struct kvm_pmu *pmu = &vcpu->arch.pmu;
>> +
>> +	pmu->irq_pending = false;
>> +}
>> +
>> +/**
>> + * kvm_pmu_init - Initialize global PMU state for per vcpu
> 
> how is this both global and per VCPU?
> 
>> + * @vcpu: The vcpu pointer
>> + *
>> + * Initialize PMC and Set all the PMU IRQ numbers to invalid
> 
> s/Set/set/
> 
>> + * value so that user space has to explicitly provide PMU
>> + * IRQ numbers using set device address ioctl.
>> + */
>> +void kvm_pmu_init(struct kvm_vcpu *vcpu)
>> +{
>> +	int i;
>> +	struct kvm_pmu *pmu = &vcpu->arch.pmu;
>> +
>> +	memset(pmu, 0, sizeof(*pmu));
>> +	for (i = 0; i < ARMV8_MAX_COUNTERS; i++) {
>> +		pmu->pmc[i].idx = i;
>> +		pmu->pmc[i].vcpu = vcpu;
>> +	}
>> +
>> +	pmu->irq_num = -1;
>> +}
>> -- 
>> 2.1.0
>>

-- 
Shannon